Numerous methods have been proposed for metal bonding of bearings. For example, U.S. Pat. No. 3,500,526, describes a method of applying bearing metal to the interior of a bearing shell. The steps of the process comprise tinning the bearing side and applying heat directly to the surface portion of the bearing side to aid in the adhesion of the tin to the bearing metal. A first pass of molten bearing metal is poured onto the heated shell portion. The adjacent shell surface is immediately cooled on the opposite side to solidify the metal deposited and to ensure the adhesion to the shell. The steps of applying heat, pouring and cooling are continued until the metal is deposited to the desired depth.
U.S. Pat. No. 2,588,421, describes a process for coating metal with a spray gun. You will note in column 1 in the paragraph beginning at line 39, that the inventor describes the use of this metal in forming or rebuilding the bearings. In column 4 in the paragraph beginning at line 53, the inventor states that the metal spraying is carried out using a metal spray gun and wire or rod as a source of metal.
U.S. Pat. No. 3,057,046, relates to a method for the manufacture of metal bearings and bearing surfaces. As it is pointed out in column 1 in the paragraph beginning at line 49, one of the steps of the process consists of applying a metal to the surface of a bearing by spraying.
Typically, in prior art methods, base metal dilution results thereby providing a weak weld between the bonding metal and the base metal. Often when babbitt metal is heated to the molten state, there is a tendency for the antimony component of babbitt to separate which compromises the integrity of the alloy.
Prior art methods also invite contamination during bonding which creates porosity in the finished bearing surface.
Prior art methods also suffer a defect in effective control of the deposit thickness with resultant waste of expensive bearing material.
In those prior art methods which require pre-heating suffer a further disadvantage in that the base metal frequently experiences distortion.
Practice of the present invention overcomes these and other disadvantages experienced in the prior art.
It is an object of the present invention to provide a bond having truer weld with minimal base metal dilution.
Another object of practice of the present invention is to provide a method wherein antimony separation of the babbitt alloy does not occur thereby maintaining the integrity of the babbitt alloy.
A further object of the present invention is to provide a shielding of the weld puddle by means of an inert gas during deposit of the babbitt alloy, thereby avoiding contamination of the molten alloy and resultant porosity in the finished bearing surface.
Yet another object of the present invention is to provide a method wherein control of deposit thickness of the bonding alloy is effected which can be closely controlled with the resultant elimination of excess waste of expensive bonding alloy.
Another further object of the present invention is to eliminate a pre-heating step of the base metal thereby minimizing base metal distortion.
These and other objects and advantages will become more apparent from the following more detailed description of the present invention.